Boring bars



C. F. NORKUS July 26, 1955 BORING BARS Filed June 28, 1951 IN VEN TOR.

ChAPL [a fA/ae/rw A TTOENEY United States Patent BORING BARS Charles F. Norkus, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application June 28, 1951, Serial No. 233,979

3 Claims. (Cl. 51184.l)

This invention relates to boring machines and more particularly to a lapping tool orlapping element holder and insert adapted to be detachably mounted on and forming a part of a boring bar. The boring bar may, for example, be employed to hone the interior surface of a shock strut cylinder, said cylinder being one of the principal parts of the shock strut mechanism of an airplane.

An object of my invention is to provide a simple, effective, and long wearing boring bar element as referred to above, said element adapted to be detachably mounted on and forming a part of a boring bar.

The most important object of my invention is to provide a long wearing lapping element holder and insert for a boring bar, said element being distinguished by the provision of a detachable insert of relatively hard and long lasting material.

Other objects of this invention and desirable details of construction and combination of parts will become apparent from the following description of a preferred embodiment of my invention which is taken in conjunction with the accompanying drawings in which:

Figure l is a perspective view disclosing, in juxtaposition with the work to be operated upon, a boring bar equipped with the pack element of my invention;

Figure 2 is a view disclosing the pack element constituting my invention; and

Figures 3 and 4 disclose, in section, two different embodiments of the pack element or lapping tool constituting my invention.

There is disclosed, in Figure 1, a boring bar including a plurality of the lapping element holders and inserts 11 constituting my invention, together with one example of work to be operated upon i. e. a cylinder 12 constituting one of the principal parts of the shock strut of an airplane or other heavier than air aircraft. The boring bar is, of

course, mounted on and operated by a lathe, not shown, or

other machine imparting a rotation of the pilot 13 of the bar about its longitudinal axis. The rotating bar 10 with its lapping elements 11 is bodily moved toward the cylinder 12, Figure l, the lapping elements entering the cylinder to perform their honing operation.

A lapping element holder support or arbor element 14 is sleeved over one end of the pilot 13, said support being constructed to provide jaws 15 for the lapping element holders 11. As is disclosed in Figure 2 each lapping element holder 11 is tapered both in width and height thereby cooperating with the correspondingly shaped jaws 15 to maintain said element holder in place as part of the boring bar. Each lapping element holder 11 is wedged in place by a friction fit thereby insuring each holder remaining in place during the honing operation of the boring bar. The pilot 13 is preferably rotatably supported at a plurality of spaced apart areas along the length thereof it being important to provide a support, not shown, immediately adjacent the lapping element holder support 14; for such a mounting of the pilot will insure the desired cutting and honing operations. The pilot 13 of Figure 1 serves, of course, as a mounting for either a cutter or the lapping element holders 11, however, only the latter elements are disclosed in this figure.

Describing now the principal feature of my invention, that is the lapping element holder per se, there is disclosed in Figure 2 one of said holders. As described above this holder is tapered both in width and height and the holder is recessed at 19 to receive a prism shaped insert 16 preferably of a tough and hard brake lining or equivalent material. A body portion 18 of the lapping element holder may be of either wood such as hard maple, Figure 3, or steel, Figure 4; and if the body portion is of Wood it is preferably impregnated, under pressure, with a preservative and lubricant such as linseed oil. As is disclosed in Figure 4 if the body portion of the lapping element holder is of steel there is preferably placed, at the base of the recess 19, a cushioning element 20 of cork, wood or other flexible material, said cushioning element serving to bias the insert member 16 outwardly to facilitate a tight fit between the outer surface of the insert and the interior surface 22 of the work, that is the cylinder 12 of the shock strut mechanism.

If the body of the lapping element holder is of wood, Figure 3, then no cushion element is necessary. The base of the body portion 18 may be provided with a plurality of knock out openings 24, Figure 3, through which a punch may be inserted to facilitate the removal of a worn out insert from the body of the lapping element holder; and if desired each insert 16 may be in two sections to facilitate an inspection of this element prior to its removal. The insert is shown in two parts in Figure 2, however the construction of the insert in one integral part is preferred.

There is thus provided a simple, compact and effective lapping element holder adapted to be mounted in and become a part of a boring bar machine. The lapping element holder together with its insert 16, Figure 2, may be operated by hand in which case it is aptly termed a lapping toolll, 16, however, as described above and disclosed in Figure 1, this tool may be used as a part of a boring bar. The lapping element holder and insert of my invention, particularly that disclosed in Figure 3, is quite efficient and effective inasmuch as the inclusion of the insert 16 saves any appreciable wear of the wooden body portion of said holder.

I claim:

1. A lapping tool adapted to be mounted in a boring bar the body portion of the tool being of steel, said body portion being tapered in width and height and provided with a recess shaped to receive an insert of relatively hard material, the bottom side of the tool, that is the side adapted to contact the boring bar, being of greater width than the top side thereof to thereby provide said taper in height and facilitate a wedge fit with a portion of the boring bar, together with a parallelopiped shaped insert mounted in a portion of said recess and a cork member positioned within the remainder of the recess and lying on the bottom thereof, said cork member serving as a cushioning means for the insert and as a means for biasing the insert outwardly.

2. The combination with the pilot of a boring bar and an arbor mounted on one end thereof, of a plurality of generally prism shaped cutting tools tapering in width and height and detachably wedged into place in the arbor the bottom side of each tool, that is the side adapted to contact the arbor, being of greater width than the top side thereof to thereby provide said taper in height, each of said tools including an insert of relatively hard material operating to increase the life of the tool.

3. A lapping tool adapted to be mounted in a boring bar the body portion of the tool being of wood, said body portion being impregnated with a material to increase the life thereof and also being tapered in width and height References Cited in the file of this patent UNITED STATES PATENTS Re. 16,138 Powell Aug. 11, 1925 Sunnen Mar. 14, Harter June 17, Emerson Dec. 17, Johnson Feb. 12, Rose et al June 8, Hingle Aug. 20, Wallace Jan. 26, McClure July 11, Jacobson Jan. 11, 

